U.S. patent number 11,066,055 [Application Number 15/378,464] was granted by the patent office on 2021-07-20 for braking system for a motor vehicle.
This patent grant is currently assigned to Continental Automotive Systems, Inc.. The grantee listed for this patent is Continental Teves AG & Co. oHG. Invention is credited to Marco Besier, Stefan Drumm.
United States Patent |
11,066,055 |
Besier , et al. |
July 20, 2021 |
Braking system for a motor vehicle
Abstract
A braking system for a motor vehicle for actuating hydraulically
actuatable wheel brakes comprises a first and a second electrically
controllable pressure source for providing a brake pressure for
actuating the wheel brakes. A first electric energy supply unit and
a second electric energy supply unit that is independent of the
first electric energy supply unit are provided. An electrically
controllable pressure modulation device for setting brake pressures
that are individual to each of the wheel brakes has at least one
electrically actuatable inlet valve for each wheel brake. The first
pressure source can be supplied with electric energy by the first
energy supply unit, the second pressure source can be supplied with
electric energy by the second energy supply unit, and the pressure
modulation device can be supplied with electric energy by the first
energy supply unit and by the second energy supply unit.
Inventors: |
Besier; Marco (Bad Schwalbach,
DE), Drumm; Stefan (Saulheim, DE) |
Applicant: |
Name |
City |
State |
Country |
Type |
Continental Teves AG & Co. oHG |
Frankfurt |
N/A |
DE |
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Assignee: |
Continental Automotive Systems,
Inc. (Auburn Hills, MI)
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Family
ID: |
53051827 |
Appl.
No.: |
15/378,464 |
Filed: |
December 14, 2016 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20170129468 A1 |
May 11, 2017 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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PCT/EP2015/060176 |
May 8, 2015 |
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Foreign Application Priority Data
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Jun 30, 2014 [DE] |
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10 2014 212 537.5 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60T
8/4086 (20130101); B60T 8/4077 (20130101); B60T
2270/413 (20130101); B60T 8/321 (20130101) |
Current International
Class: |
B60T
13/68 (20060101); B60T 8/40 (20060101); B60T
8/32 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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103029698 |
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Apr 2013 |
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CN |
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103492247 |
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Jan 2014 |
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CN |
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102008060029 |
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Jun 2010 |
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DE |
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102008060029 |
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Jun 2010 |
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DE |
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102011081461 |
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Mar 2012 |
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DE |
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102011084206 |
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Apr 2012 |
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DE |
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102011084206 |
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Apr 2012 |
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DE |
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102012201535 |
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Oct 2012 |
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DE |
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102012020322 |
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Apr 2014 |
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DE |
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102013225809 |
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Aug 2014 |
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DE |
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2009227093 |
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Oct 2009 |
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JP |
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WO2012028521 |
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Mar 2012 |
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WO |
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WO-2012143313 |
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Oct 2012 |
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WO |
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WO2012150120 |
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Nov 2012 |
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WO |
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Other References
International Search Report and Written Opinion dated Jul. 20, 2015
from corresponding International Patent Application No.
PCT/EP2015/060176. cited by applicant .
German Search Report dated Apr. 20, 2015 for corresponding German
Patent Application No. 10 2014 212 537.5. cited by applicant .
China Office Action dated Aug. 5, 2018 for corresponding Chinese
Patent Application No. 201580034854.4. cited by applicant.
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Primary Examiner: King; Bradley T
Assistant Examiner: Bowes; Stephen M
Claims
What is claimed is:
1. A braking system for a motor vehicle for operating hydraulic
wheel brakes comprising: a first electrically controllable
hydraulic pressure source for providing a brake pressure for
operation of each of the wheel brakes; a second electrically
controllable hydraulic pressure source for providing the brake
pressure for operation of each of the wheel brakes; a first
electrical power supply unit; a second electrical power supply unit
that is independent of the first electrical power supply unit; an
electrically controllable hydraulic pressure modulation device for
setting wheel-specific brake pressures for the wheel brakes with at
least one inlet valve that can be operated electrically for each of
the wheel brakes; wherein the first hydraulic pressure source can
be supplied with electrical energy exclusively by the first power
supply unit, the second hydraulic pressure source can be supplied
with electrical energy exclusively by the second power supply unit,
the hydraulic pressure modulation device and the at least one inlet
valve are supplied with electrical energy by the first power supply
unit and the second power supply unit; and wherein the second
hydraulic pressure source is hydraulically disposed between the
first hydraulic pressure source and the hydraulic pressure
modulation device.
2. The braking system of claim 1, further comprising: a first
electronic control and regulating unit for actuating the first
hydraulic pressure source; a second electronic control and
regulating unit for actuating the second hydraulic pressure source;
and a third electronic control and regulating unit configured to
actuate the hydraulic pressure modulation device.
3. The braking system of claim 2, wherein the first electronic
control and regulating unit is supplied with electrical energy by
the first power supply unit, the second electronic control and
regulating unit is supplied with electrical energy by the second
power supply unit, and the third electronic control and regulating
unit is supplied with electrical energy by either one of the first
power supply unit and the second power supply unit.
4. The braking system of claim 2, further comprising wheel
revolution rate sensors connected to the braking system, wherein
signals of the wheel revolution rate sensors are received by the
third electronic control and regulating unit.
5. The braking system of claim 2, wherein the first, the second and
the third control and regulating units are connected to each other
by data busses.
6. The braking system of claim 2, wherein at least one of the
control and regulating units is connectable by a data
communications path to a fourth electronic control and regulating
unit in which an autopilot function is carried out.
7. The braking system of claim 6, wherein at least the first and
the second control and regulating units are connectable to the
fourth control and regulating unit by respective data
communications paths.
8. The braking system of claim 1, further comprising a sensor
device connected to the braking system, which detects a yaw rate of
the motor vehicle, a lateral acceleration of the motor vehicle,
and/or a longitudinal acceleration of the motor vehicle.
9. The braking system of claim 1, wherein the first controllable
hydraulic pressure source comprises a master brake cylinder with an
electrically controllable brake force booster connected upstream
thereof.
10. The braking system of claim 9, wherein the electrically
controllable brake force booster further comprises an electrically
controllable electro-mechanical actuator with an electric motor and
a translation-rotation gearbox, which operates a piston of the
master brake cylinder.
11. The braking system of claim 9, wherein the electrically
controllable brake force booster comprises a hydraulic
cylinder-piston arrangement, the piston of which can be displaced
by an electro-mechanical actuator, wherein the master brake
cylinder can be operated by the cylinder-piston arrangement.
12. The braking system of claim 1, wherein the second hydraulic
pressure source comprises an electrically controllable pressure
booster with a motor-pump assembly and electrically operated valves
for setting the brake pressures that are redirected to the
hydraulic pressure modulation device.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
This U.S. patent application claims the benefit of PCT patent
application No. PCT/EP2015/060176, filed May 8, 2015, which claims
the benefit of German patent application No. 10 2014 212 537.5,
filed Jun. 30, 2014, both of which are hereby incorporated by
reference.
TECHNICAL FIELD
The invention concerns a braking system for a motor vehicle.
BACKGROUND
In motor vehicle technology, "brake-by-wire" braking systems are
becoming ever more widespread. Such braking systems often comprise,
besides a master brake cylinder that can be operated by the driver
of the vehicle, an electrically controllable pressure supply
device, by means of which the hydraulic pressure for operation of
the wheel brakes is built up in the "brake-by-wire" operating mode.
The existence of a "brake-by-wire" operating mode of the braking
system is the prerequisite for automated driving, during which an
electronic autopilot function steers, accelerates and brakes the
vehicle either fully automatically or in cooperation with the
driver.
In order to meet the safety requirements for automated driving, in
particular performing braking without operation of the brake pedal
by the driver, even in the event of a failure of the electrically
controllable pressure supply device, a second, independent device
for the electrically controllable supply of brake pressure is
necessary.
From DE 10 2011 084 206 A1, a braking system for motor vehicles is
known with a master brake cylinder that can be electrically
operated by an electrohydraulic actuator, a motor-pump assembly and
a wheel brake pressure modulation unit with an inlet valve and an
outlet valve per wheel brake. Two electronic control and regulating
units are provided, wherein the first control and regulating unit
is used for actuating the motor-pump assembly and the wheel brake
pressure modulation unit and the second control and regulating unit
is used for actuating the electrohydraulic actuator for operating
the master brake cylinder. Furthermore, two separate power supplies
are provided, wherein the first power supply supplies the first
control and regulating unit with electrical energy and the second
power supply supplies the second control and regulating unit with
electrical energy. In the event of a failure of the first power
supply, only a uniform brake pressure build-up or reduction on all
wheel brakes is possible by means of the electrohydraulic actuator.
The setting of wheel-specific brake pressures, in particular
anti-lock braking control (ABS: Anti-lock Braking System) or
driving dynamics control (ESC: Electronic Stability Control) or
another stabilizing assistance function of the braking system, is
not possible in the known braking system in this case.
The background description provided herein is for the purpose of
generally presenting the context of the disclosure. Work of the
presently named inventors, to the extent it is described in this
background section, as well as aspects of the description that may
not otherwise qualify as prior art at the time of filing, are
neither expressly nor impliedly admitted as prior art against the
present disclosure.
SUMMARY
It is therefore the object of the present invention to provide a
braking system for a motor vehicle that meets the safety
requirements for automated driving.
A braking system is provided with improved availability of
assistance functions with wheel-specific brake pressure regulation
or control. The first pressure source can be supplied with
electrical energy by a first power supply unit, the second pressure
source can be supplied with electrical energy by a second power
supply unit that is independent of the first power supply unit and
the pressure modulation device can be supplied with electrical
energy by the first power supply unit and the second power supply
unit.
Following a failure of one of the power supply units, one of the
pressure sources as well as the pressure modulation device can
always still be supplied with electrical energy in order to enable
wheel-specific brake pressure regulation and thereby safe braking
to be carried out. The pressure modulation device has at least one
electrically operated inlet valve for each wheel brake. Preferably,
an electrically operated inlet valve and an electrically operated
outlet valve are provided for each wheel brake. Wheel-specific
brake pressures are derived by means of the pressure modulation
device from the brake pressure provided from the first pressure
source or the brake pressure provided from second pressure source
or the brake pressure provided by means of both pressure
sources.
The second pressure source is hydraulically disposed between the
first pressure source and the pressure modulation device. This
enables boosting of the pressure output by the first pressure
source to be carried out when required.
The first pressure source can be exclusively supplied with
electrical energy by the first power supply unit and the second
pressure source can be exclusively supplied with electrical energy
by the second power supply unit. This achieves a smaller number of
supply lines from the power supply units to the pressure sources
compared to a braking system in which at least one of the two
pressure sources can be supplied by the first and the second power
supply units.
According to an embodiment, the braking system comprises a first
electronic control and regulating unit associated with the first
pressure source for actuating the first pressure source, a second
electronic control and regulating unit associated with the second
pressure source for actuating the second pressure source and a
third electronic control and regulating unit associated with the
pressure modulation device for actuating the pressure modulation
device. Owing to the separately implemented third control and
regulating unit for the pressure modulation device, the increased
availability of wheel-specific brake pressure regulation functions
can be achieved.
The pressure modulation device can be implemented as a standalone
hydraulic unit. The pressure modulation device and the third
electronic control and regulating unit are implemented as an
electrohydraulic control unit.
According to an embodiment of the braking system, the first
electronic control and regulating unit can be supplied with
electrical energy by the first power supply unit, the second
electronic control and regulating unit can be supplied with
electrical energy by the second power supply unit and the third
electronic control and regulating unit can be supplied with
electrical energy by the first power supply unit and by the second
power supply unit. Following a failure of the first or the second
control and regulating unit, one of the pressure sources as well as
the pressure modulation device can always still be supplied with
electrical energy, in order to thus be able to carry out
wheel-specific brake pressure regulation and thereby safe
braking.
The first and the second pressure sources and the pressure
modulation device are supplied with electrical energy by the
electronic control and regulating unit associated therewith.
In order to be able to implement anti-lock braking controls, the
braking system comprises or is connected to wheel revolution rate
sensors, wherein the signals of the wheel revolution rate sensors
are delivered to the third control and regulating unit. The
processing of the signals is carried out in the third control and
regulating unit, so that the necessary data for actuating the
pressure modulation device during wheel-specific brake pressure
regulation are also available in the event of a failure of the
first or second control and regulating unit.
The braking system may additionally comprises or is connected to a
sensor device for detecting driving dynamics variables, wherein the
signals of the sensor device are delivered to the third control and
regulating unit, which is associated with the pressure modulation
device. The processing of the signals is particularly preferably
carried out in the third control and regulating unit. This enables
driving dynamic, wheel-specific brake pressure regulation, even in
the event of a failure of the first or second control and
regulating unit.
The sensor device preferably comprises at least one sensor for
detecting the yaw rate of the motor vehicle, at least one sensor
for detecting the lateral acceleration of the motor vehicle and/or
a sensor for detecting the longitudinal acceleration of the motor
vehicle.
The first, the second and the third control and regulating units
are preferably connected to each other by data buses.
In order to carry out automated driving, according to a development
of the braking system at least one of the three control and
regulating units is or can be connected to a fourth electronic
control and regulating unit by a data communications path in which
an autopilot function is carried out.
In order to be able to carry out an independent pressure build-up
by each of the two pressure sources, at least the first and the
second control and regulating units are or can be connected to the
fourth control and regulating unit by means of a respective data
communications path. However, each of the three control and
regulating units is or can be connected to the fourth control and
regulating unit by means of one data communications path. The data
communications path consists of a data bus.
According to an embodiment of the braking system, the second
pressure source comprises a motor-pump assembly with an at least
dual-circuit hydraulic pump. Such assemblies have been known for a
long time and can produce high pressures and can be implemented in
very compact sizes.
Furthermore, the second pressure source preferably comprises
electrically operated valves for setting the brake pressure or the
brake pressures that is or are redirected to the pressure
modulation device. Valves are also provided that enable the
separation of the connection between the first pressure source and
the pressure modulation device.
Other objects, features and characteristics of the present
invention, as well as the methods of operation and the functions of
the related elements of the structure, the combination of parts and
economics of manufacture will become more apparent upon
consideration of the following detailed description and appended
claims with reference to the accompanying drawings, all of which
form a part of this specification. It should be understood that the
detailed description and specific examples, while indicating the
preferred embodiment of the disclosure, are intended for purposes
of illustration only and are not intended to limit the scope of the
disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
The present disclosure will become more fully understood from the
detailed description and the accompanying drawings, wherein:
FIG. 1 shows a first exemplary embodiment of a braking system;
and
FIG. 2 shows a second exemplary embodiment of a braking system.
DETAILED DESCRIPTION
The braking system according to the example according to FIG. 1
essentially comprises a first electrically controllable pressure
source 2 for the provision of a brake pressure for the operation of
the wheel brakes 1 of a motor vehicle that is not shown, a second
electrically controllable pressure source 3 for the provision of a
brake pressure for the operation of the wheel brakes 1, an
electrically controllable pressure modulation device 6 for setting
wheel-specific brake pressures for the wheel brakes 1, a first, a
second and a third electronic control and regulating unit (ECU) 12,
13, 16 as well as a first electrical power supply unit 4 and a
second electrical power supply unit 5 that is independent of the
first electrical power supply unit.
The first electronic control and regulating unit 12 is associated
with the first pressure source 2 and is used for actuating the
first pressure source 2. The second electronic control and
regulating unit 13 is associated with the second pressure source 3
and is used for actuating the second pressure source 3 and the
third electronic control and regulating unit 16 is associated with
the pressure modulation device 6 and is used for actuating the
pressure modulation device 6.
The first electrically controllable pressure source 2 comprises a
dual circuit master brake cylinder 7 with two pistons 9, 22 that
are disposed one after the other and that bound two hydraulic
pressure chambers 21, 23. On the one hand, the pressure chambers
21, 23 are connected by means of radial bores formed in the pistons
9, 22 as well as corresponding pressure equalization lines 20a, 20b
to a pressure medium reservoir container 70 that is under
atmospheric pressure, wherein said connection can be shut off by a
relative displacement of the pistons 9, 22 in the housing 24. On
the other hand, each of the pressure chambers 21 or 23 is connected
to the pressure modulation device 6 by means of a hydraulic
connection 26a or 26b. The pressure chambers 21, 23 accommodate
unspecified restoring springs, which position the pistons 9, 22 in
an initial position when the master brake cylinder 7 is not
operated.
Furthermore, the first controllable pressure source 2 comprises an
electrically controllable brake force booster 8 that is connected
upstream of the master brake cylinder 7. According to the example,
the brake force booster 8 comprises an electrically controllable
electromechanical actuator that is not shown in detail, by means of
which the piston 9 of the master brake cylinder 7 can be
operated.
The operation of the brake pedal 10 of the braking system is
detected for example by means of a travel sensor or an angle sensor
that is not shown, for example in the brake force booster 8, and
the sensor signal is redirected to the first electronic control and
regulating unit 12, which is associated with the first pressure
source 2.
If boosted braking is to be carried out, the control and regulating
unit 12 actuates the electromechanical actuator of the brake force
booster 8. According to the example, the electromechanical actuator
comprises an electric motor and a rotation-translation gearbox, by
means of which the desired operating force can be exerted on the
piston 9 of the master brake cylinder 7.
Between the first and the second control and regulating units 12,
13 there is a signal or data line 29, by means of which the first
control and regulating unit 12 can transmit a condition status for
the first pressure source to the second control and regulating unit
13. For example, in the event of a fault in the first pressure
source 2, the first control and regulating unit 12 can transmit a
fault message to the second control and regulating unit 13.
Alternatively or additionally, the first control and regulating
unit 12 can transmit an "in order" signal to the second control and
regulating unit 13 if the first pressure source is operational. In
both cases, using the transmitted condition status of the first
pressure source, the second control and regulating unit 13 can
detect whether the second pressure source 3 should be actuated for
operation of the wheel brakes.
Owing to the hydraulic series connection of the two pressure
sources, a build-up of the pressure at the pressure modulation
device (so-called modulator inlet pressure) is guaranteed even if
the first pressure supply is not operationally ready, for example
as a result of a failure of the first electrical power supply, and
the first control and regulating unit 12 also sends no
corresponding fault signal. For said case, for the independent
operation of the wheel brakes and suitable actuation of the second
pressure source 3, advantageously two further independent
displacement sensors 25 and 27 are provided, which for example
detect a displacement of the pistons 9 and 22, and the signals of
which are transmitted to the second electronic control and
regulating unit 13, which is associated with the second pressure
source 3, by means of a signal or data line 28.
According to the example, the second electrically controllable
pressure source 3 is implemented as a standalone hydraulic unit,
which is hydraulically disposed between the first pressure source 2
and the pressure modulation device 6.
The hydraulic unit 3 and the electronic unit are preferably
implemented as an electrohydraulic control unit (HECU).
Pressure source 3 essentially comprises an electrically
controllable pressure supply device 30, which according to the
example is implemented as a dual circuit motor-pump assembly, as
well as electrically operated valves 31a, 32a, 33a, 34a, 31b, 32b,
33b, 34b for setting the brake pressure of each brake circuit or of
each hydraulic line 26a or 26b that is redirected to the pressure
modulation device 6. Other embodiments of the second pressure
source are possible, for example with a different pressure supply
device and/or a different valve combination.
According to the example, the motor-pump assembly 30 comprises two
pumps 38a, 38b that are driven in common by an electric motor 37.
The motor-pump assembly is preferably in the form of a type of
piston pump driven by the electric motor by means of a cam, a type
of construction of which millions are already used as recirculation
pumps in known brake systems. These can produce particularly high
system pressures and can be implemented in very compact sizes.
According to the example, four electrically operated valves 31a,
32a, 33a, 34a, or 31b, 32b, 33b, 34b as well as two pressure
sensors 35a, 36a or 35b, 36b are provided for each brake
circuit.
A respective normally open, advantageously analog actuated pressure
relief valve 32a, 32b, by means of which the hydraulic connection
between the master brake cylinder pressure chamber 21, 23 and the
pressure modulation device 6 can be disconnected, is disposed in
each of the connections 26a, 26b. An unspecified non-return valve
that opens towards the pressure modulation device 6 is connected in
parallel with each pressure relief valve 32a, 32b. The pressure
upstream and downstream of the pressure relief valve 32a, 32b is
measured by means of the pressure sensors 35a, 36a or 35b, 36b.
In each brake circuit the suction port of the pump 38a, 38b is
connected to a recirculation line 64a, 64b leading to the pressure
medium reservoir container 70, so that pressure medium can be
sucked out of the pressure medium reservoir container 70. The
respective pressure port of the pump 38a, 38b is connected to the
associated input port of the pressure modulation device by means of
a non-return valve 39a, 39b opening towards the pressure modulation
device 6. The pump 38a, 38b is in each case connected in parallel
with a normally open, advantageously analog actuated pressure
relief valve 33a, 33b. Furthermore, the suction port of the pump
38a, 38b is in each case connected by means of a hydraulic
connection to the region of the connection 26a, 26b on the master
brake cylinder pressure chamber side, wherein a series connection
of a normally closed reduction-release valve 31a, 31b and the
normally open, advantageously analog actuated reduction-metering
valve 34a, 34b is provided in the hydraulic connection from the
connection 26a, 26b.
The pressure modulation device 6 is implemented as a standalone
hydraulic unit and according to the example comprises for each
wheel brake 1 an inlet valve 60a-60d and an outlet valve 61a-61d
that are hydraulically connected to each other in pairs by means of
center connections and are connected to the wheel brake 1. The
input ports of the inlet valves 60a-60d are supplied with a
pressure from the second pressure source 3 for each brake circuit
I, II (modulator inlet pressure). With the pressure source 3 not
activated, said pressures correspond to the master brake cylinder
pressures. In each case an unspecified non-return valve opening
towards the second pressure source 3 is connected in parallel with
the inlet valves 60a-60d. The output ports of the outlet valves
61a, 61b; 61c, 61d of each brake circuit are connected to the
pressure medium reservoir container 70 by means of the associated
recirculation lines 64a, 64b. A different implementation of the
pressure modulation device 6 is possible in principle.
The third electronic control and regulating unit 16 associated with
the pressure modulation device is connected to the second
electronic control and regulating unit 13 by means of a signal or
data line 62, for example a data bus. The third control and
regulating unit 16 can thus request an additional pressure build-up
from the second control and regulating unit 13 (for example for the
ESC function).
The hydraulic unit 6 and the electronic unit are preferably
implemented as an electrohydraulic control unit (HECU).
The first pressure source 2 is supplied with electrical energy by
means of a supply line 40 from the first power supply unit 4 and
the second pressure source 3 is supplied with electrical energy
from the second power supply unit 5 by means of a supply line 50.
For supplying the pressure modulation device 6 with electrical
energy, means 45 are provided, using which the pressure modulation
device 6 can be supplied by the first power supply unit 4, by the
second power supply unit 5 or by both power supply units. In this
case, a switchable current or voltage supply can be used for
example, so that the pressure modulation device 6 is optionally
supplied from the first power supply unit 4 or the second power
supply unit 5.
In order to be able to implement anti-lock braking control,
according to the example the braking system comprises a wheel
revolution rate sensor 99 for each wheel of the motor vehicle. So
that the signals of the wheel revolution rate sensors 99 are
available for anti-lock braking control, even in the event of a
failure of one of the power supply units 4, 5 or in the event of a
failure of one of the control and regulating units 12, 13, the
signals of the wheel revolution rate sensors 99 are delivered to
the control and regulating unit 16 of the pressure modulation
device 6. According to the example, the wheel revolution rate
signals are processed and analyzed in the control and regulating
unit 16. The wheel revolution rate sensors 99 are advantageously
supplied with electrical energy from the control and regulating
unit 16.
In order to be able to implement a driving dynamics control
function or a stabilizing assistance function, according to the
example the braking system further comprises a sensor device 14 for
detecting driving dynamics variables, the signals of which are
delivered to the control and regulating unit 16 of the pressure
modulation device 6 by means of a signal or data line 63,
implemented for the same reasons as above, and are preferably also
processed and analyzed there. The sensor device 14 is
advantageously supplied with electrical energy from the control and
regulating unit 16.
According to the example, the sensor device 14 comprises a sensor
for detecting the yaw rate of the motor vehicle and a sensor for
detecting the lateral acceleration of the motor vehicle. Sensor
device 14 also comprises a sensor for detecting the longitudinal
acceleration of the motor vehicle. Furthermore, the sensor device
14 preferably comprises a steering angle sensor or a steering wheel
angle sensor.
A second exemplary embodiment of a braking system according to the
invention is schematically represented in FIG. 2.
The braking system differs from the first exemplary embodiment
shown in FIG. 1 essentially by the implementation of the first
pressure source. Matching elements are therefore provided with the
same reference characters in F.1 and 2.
According to the second exemplary embodiment, the braking system
essentially comprises a first electrically controllable pressure
source 102 and a second electrically controllable pressure source 3
for the provision of a brake pressure for the operation of the
wheel brakes 1, an electrically controllable pressure modulation
device 6 for setting wheel-specific brake pressures for the wheel
brakes 1, a first electronic control and regulating unit 112
associated with the first pressure source 102, a second electronic
control and regulating unit 13 associated with the second pressure
source 3 and a third electronic control and regulating unit 16
associated with the pressure modulation device 6 as well as a first
electrical power supply unit 4 and a second electrical power supply
unit 5 that is independent of the first power supply unit.
According to the example, the second electrically controllable
pressure source 3 and the pressure modulation device 6 are
implemented as in the first exemplary embodiment.
According to the second exemplary embodiment, the first control and
regulating unit 112 or the first pressure source 102 is supplied
with electrical energy from the first power supply unit 4 and the
second control and regulating unit 13 or the second pressure source
3 is supplied with electrical energy from the second power supply
unit 5. Means 45 are provided for supplying power to the third
control and regulating unit 16 or the pressure modulation device 6
that enable the supply by means of the first power supply unit 4 or
by means of the second power supply unit 5. In addition, supply by
means of both power supply units can also be possible.
According to the example, wheel revolution rate sensors 99 as well
as a sensor device 14 for detecting driving dynamics variables are
provided, the signals of which are delivered to the control and
regulating unit 16 and which are supplied with electrical energy
from the control and regulating unit 16. An exchange of data
between the third control and regulating unit 16 and the second
control and regulating unit 13 is possible by means of the signal
or data line 62.
The first electrically controllable pressure source 102 comprises a
dual circuit master brake cylinder 7 according to the first
exemplary embodiment, the pressure chambers 21, 23 of which are
connected to the pressure modulation device 6 by means of hydraulic
connections 26a, 26b. The pressure source 102 further comprises an
electrically controllable brake force booster 108, which is
connected upstream of the master brake cylinder 7.
According to the example, the brake force booster 108 comprises a
hydraulic cylinder-piston arrangement, the piston 101 of which
bounds a pressure chamber 103 and can be operated by a
schematically indicated electromechanical actuator 109, for example
an electric motor and a rotation-translation gearbox that is
connected downstream. A rotor position sensor that is used for
detecting the rotor position of the electric motor and that is only
schematically indicated is denoted by the reference character 104.
In addition, a temperature sensor 105 can also be used for
detecting the temperature of the motor winding.
The brake pedal 10 of the braking system is mechanically couple to
a piston 110 with an annular surface 111, which mechanically
operates the first master brake cylinder piston 9 in the event of a
displacement in the brake operating direction. The annular surface
111, with the housing 24, bounds a hydraulic chamber 107, wherein a
pressure acting in the chamber 107 corresponds to a force acting on
the first master brake cylinder piston 9 in the brake operating
direction. The pressure chamber 103 of the cylinder-piston
arrangement is connected to the chamber 107 by means of a
connection 106, so that the master brake cylinder piston 9 can be
operated by actuating the electromechanical actuator 109.
According to the example, two independent displacement sensors 25
and 27, which for example detect a displacement of the pistons 9
and 22, are associated with the first pressure source 102 and the
signals thereof are transmitted by means of the signal or data line
28 to the second electronic control and regulating unit 13 that is
associated with the second pressure source 3. Furthermore, a force
sensor 113 that is associated with the first pressure source 102
detects a brake pedal operating force that is applied by the
driver. The signals thereof are provided to the first electronic
control and regulating unit 112 by means of a signal or data line
114.
Between the first and the second control and regulating units 112,
13 there is advantageously a signal or data line 29, for example a
data bus, by means of which the units can exchange data and by
means of which the first control and regulating unit 112 can
transmit a condition status for the first pressure source 102 for
example to the second control and regulating unit 13, as has been
described above using the first exemplary embodiment of FIG. 1.
According to the second exemplary embodiment, a fourth electronic
control and regulating unit 150 is provided, in which an autopilot
function is carried out. Such a fourth control and regulating unit
150 can also be provided according to FIG. 1. According to the
example, the fourth control and regulating unit 150 is connected to
the first, second and third control and regulating units 112, 13,
16 by means of respective data busses 151, 152, 153. Instead of a
data bus, a different data communications path is conceivable, for
example a wireless transmission/connection.
Advantageously, the third control and regulating unit 16 takes care
of all driving dynamics control tasks and the two other control and
regulating units 12, 112; 13 only have the task of providing the
two brake circuit pressures in the form of the modulator inlet
pressures. The target pressure setting for the corresponding
pressure regulator results from the braking intention of the driver
and electronic autopilots as well as brake pressure demands of the
driving dynamics ECU 16--for example for performing ESC or rollover
prevention interventions.
It is provided that only the first pressure source is used with
simple comfort braking, whereas the second pressure source always
supports the build-up of the modulator inlet pressure if either the
first pressure source has failed or the dynamics thereof or the
maximum pressure thereof is not sufficient to service the brake
pressure demand.
The driver informs the braking system of his intention to brake by
means of the brake pedal force and the brake pedal travel.
According to the legal regulations for motor vehicle brake systems,
a further operating option is preferably provided, which is
implemented for example by means of the operating element of an
electrical parking brake.
The electronic autopilot may be implemented as a computer network
that is located in the motor vehicle (fourth electronic control and
regulating unit 150). However, it is also conceivable that the
motor vehicle is remotely controlled. For example, a human operator
or an external computer network could undertake the autopilot
function, for example in order to park the vehicle in a car park.
In any case the intention to brake by the autopilot must be
reliably transferred to the braking system and reliably implemented
there. For this purpose, it is advantageously provided that the
autopilot's intention to brake is passed to the first and second
control and regulating units 112, 13 on separate data
communications paths (according to the example data buses 151,
152).
The exemplary embodiment of FIG. 2 even provides the possibility of
carrying out the data transmission of the autopilot's intention to
brake more reliably by passing the information to the third control
and regulating unit 16 on a third independent data communications
path (according to the example data bus 153).
In the braking systems according to the example there are two
mutually independent instances with mutually independent power
supplies (according to the example pressure source 2 or 102 with
power supply unit 4 and pressure source 3 with power supply unit
5), which can provide hydraulic actuation energy for the operation
of the wheel brakes 1 in a controlled manner.
In order to achieve the requirements for automated driving and in
particular high availability of wheel-specific brake pressure
regulation for assistance functions (such as for example ABS, ESC),
the pressure modulation device 6 is hydraulically separated from
the other hydraulic components and is equipped with a dedicated
control and regulating unit 16. The redundant electrical power
supply 4, 5 is used for automated driving in order to increase the
availability of the assistance functions.
The two independent instances for the controlled provision of
hydraulic actuation energy are essentially formed by an
electrically controllable brake force booster 8 or 108 and an
electrically controllable pressure booster 3.
It is sufficient to only supply the pressure modulation device 6
with electrical energy redundantly (4 and 5) and to supply the two
pressure sources 2 (or 102), 3 singly in each case from different,
mutually independent power supplies 4, 5.
The braking systems according to the example give the advantage
that following the failure of one of the power supplies 4, 5 or one
of the control and regulating units 12 (or 112), 13 of the power
sources, there is still always a pressure source 2 (or 102) or 3
and the pressure modulation device 6 available to carry out the
required safe braking function for automated driving.
The foregoing preferred embodiments have been shown and described
for the purposes of illustrating the structural and functional
principles of the present invention, as well as illustrating the
methods of employing the preferred embodiments and are subject to
change without departing from such principles. Therefore, this
invention includes all modifications encompassed within the scope
of the following claims.
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